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Europe’s comet-chasing space probe Rosetta performed its final task, dipping out of orbit for a slow-motion crash onto the surface of the alien world it’s followed for more than a decade.

Mission controllers lost contact with the probe as expected after it hit the surface of comet 67P/Churyumov-Gerasimenko, marking the planned end of a 12-year mission, the European Space Agency (ESA) said.

Farewell Rosettta, you’ve done the job. That is space science at its best

Rosetta was never designed to land. ESA used the final hours to get one-off chance to peer at mysterious markings and get otherwise unobtainable data.

Scientists ordered it to fire its thrusters for 208 seconds and perform a series of measurements as it swooped toward the surface of the 4km-wide comet. Rosetta’s science instruments were primed to sniff the comet’s gassy coma, or halo, measure its temperature and gravity, and take pictures from closer than ever before.

“We will get into a region that we have never sampled before,” said Rosetta project scientist Matt Taylor before the descent. “We’ve never been below 2km and that region is where the coma, the comet atmosphere, becomes alive, it’s where it goes from being an ice to a gas.”

Because of the distance between the comet and earth, confirmation of the impact at 1039 GMT took about 40 minutes to reach ESA’s mission control in Darmstadt, Germany.

Jan Woerner, the head of the European Space Agency, said the €1.4 billion (HK$12.1 billion) mission was already a success. Aside from sending a lander onto the surface of comet 67P in November 2014 – a cosmic first – the Rosetta mission has collected vast amounts of data that researchers will spend many more years analysing.

Scientists have already heralded a number of discoveries about the chemical composition of the comet that provide crucial insights into the formation of the solar system and theories about the origin of life on earth.

With the comet zipping through space at over 14km per second, the craft was programmed to descend at about 90cm per second – roughly half walking speed – giving Rosetta a chance to snap some unprecedented low-altitude images of the comet that could reveal surface features as small as an inch.

The command for Rosetta to leave its orbit was received when the probe was at a distance of 720 million kilometres from earth. Andrea Accomazzo, the spacecraft operations manager, said the mission had been a huge challenge and should be considered an achievement “not just for ESA, but for mankind”. Should earth ever be threatened by an asteroid, the experience gained from the Rosetta mission would prove valuable, he said.

Scientists at the control centre clapped as hugged after screens showed the loss of signal as Rosetta touched down on the comet.

“Thank you Rosetta,” ESA Director General Jan Woerner tweeted after the landing. “It’s mixed emotions,” Taylor said of the mission’s end. “We’ve only just started to get an understanding of what the data is telling us, putting together the pieces of the puzzle ... We’ve got this massive puzzle ... and we need to put them together.”

The first-ever mission to orbit and land on a comet was approved in 1993 to explore the origins and evolution of our solar system – of which comets are thought to contain primordial material preserved in a deep-space freeze. Comets of 67P’s type, however, certainly did not bring water, scientists have concluded.

Rosetta and lander probe Philae travelled more than 6 billion kilometres over 10 years to reach 67P in August 2014. Philae was sent to the comet surface in November of that year, but crash-landed and instead of lasting up to six weeks, it went into standby mode after just 60 hours.

Rosetta’s comet is currently speeding away from the sun on its near seven-year orbit.

Rosetta was programmed to switch off on impact, to make sure its signals do not interfere with any future space missions.